Separator for separating envelopes from a stack

ABSTRACT

A method for separating envelopes from a stack using a separator having a feeding roller for exerting a force onto the envelope, urging it in a direction tangential to its circumference and parallel to a separating plane, and having a deflecting surface for deflecting a leading edge of the envelope as it is urged in the tangential direction. The feeding roller and the deflecting surface bound a feeding path having a width, and starting at the separating position. Both feeding roller and deflecting surface include portions each extending from or from beyond opposite lateral sides of the feeding path inwardly across a lateral outer portion of the feeding path.

FIELD AND BACKGROUND OF THE INVENTION

This invention is a continuation application of application Ser. No.12/023,433, filed on Jan. 31, 2008, which claims priority from EP07002072.2, filed on Jan. 31, 2007, which is incorporated herein byreference.

The invention relates to a separator for separating envelopes from astack. Some examples of separators for separating sheets from a stack bybending sheets are described in European patent application 0 615 937,U.S. Pat. No. 6,883,798 and Japanese patent application 632 888 41. Insuch separators, a feeding roller is positioned relative to a sheetholder for contacting an outer sheet of a stack and for exerting afriction force onto the sheet for urging the sheet in a directiontangential to the circumference of the roller. A deflecting surface islocated spaced from the contact area in the tangential direction andextends at an angle to the sheet to be separated for deflecting aleading edge of the sheet in the separating position as it is urged pastthe deflecting surface.

In such separators, the separation is enhanced by the stiffness of thesheets that refrains sheets from passing through the curved passagebound by the deflecting surface. To accommodate for variations in thestiffness of the sheets, it is described to provide moveably attachedcorner prowls and a pivotably mounted friction pads to ensure reliableseparation of the outer sheet from a stack from the next sheets.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a simple separator,which is specifically suitable for separating envelopes from a stack.

According to the present invention, this object is achieved by providinga separator for separating envelopes from a stack, consisting of aholder including a support, for holding the stack with an outer one ofthe envelopes in a separating position in a separating plane, at leastone feeding roller having a circumference and positioned relative to theholder for contacting the envelope in the separating position in acontact area of its circumference, and for exerting a friction forceonto the envelope for urging the envelope in a direction tangential tothe circumference and parallel to the separating plane; and at least onedeflecting surface spaced from the contact area in the tangentialdirection, the at least one deflecting surface extending at an angle tothe separating plane at least from a position in the separating plane,for deflecting the leading edge of the envelope in the separatingposition as it is urged in the tangential direction along the separatingplane and passes along the at least one deflecting surface; wherein theat least one feeding roller and the at least one deflecting surfacebound a feeding path starting at the separating position, the feedingpath having a width; wherein the at least one feeding roller includestwo portions extending from or from beyond opposite lateral sides of thefeeding path inwardly across at least lateral outer portions of thefeeding path; wherein the at least one deflecting surface includes twoportions extending from or from beyond opposite lateral sides of thefeeding path inwardly across at least lateral outer portions of thefeeding path; and wherein the deflecting surface has a frictioncoefficient uniform across its width.

The feeding roller and deflection surface sections extending from bothlateral edges of the feeding path inwardly contact the envelope to beseparated in areas along opposite lateral side edges of the envelope.The edge areas of the envelope, where the front and rear walls of theenvelope are connected to each other, are the stiffest areas of theenvelope and therefore have the greatest resistance against bending.Accordingly, by bending the envelope around the feeding roller in theseareas, the greatest resistance against passing the deflection surface iscaused, which is favorable for avoiding double feeds in which an outerenvelope to be separated entrains a next envelope. Also, engaging theenvelopes in an area where the bending stiffness is greatest makes theseparation relatively insensitive to variations in bending stiffnessbetween envelopes and proper adjustment of the deflecting surface.Because the friction coefficient of the deflecting surface relative tothe envelopes is uniform across its width, the friction force exerted onthe envelope is affected only to a small extent by the width of theenvelope.

Particular elaborations and embodiments of the invention are set forthin the dependent claims.

Further features, effects and details of the invention appear from thedetailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of an example of a separatoraccording to the invention;

FIG. 2 is a schematic side view of the separator of FIG. 1;

FIG. 3 is schematic front view of the separator of FIGS. 1 and 2; and

FIG. 4 is a schematic perspective view of another example of a separatoraccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention is first described with reference to the example shown inFIGS. 1-3.

The separator 1 according to the present example is equipped with aholder 3 for holding a stack of envelopes 2 with an outer envelope 5 ina separating position, a feeding roller 4 and a deflecting surface 7.The feeding roller 4 and the deflecting surface 7 bound a feeding pathhaving a width, and starting at the separating position.

The holder 3 supports the stack 2 of envelopes to be separated. Theholder 3 has lateral guides 11 (not shown in FIG. 1) for maintaining theenvelopes positioned by contacting lateral edges of the envelopes. Theguides 11 are adjustable in the lateral direction by rotating a threadedspindle 12, for adapting the mutual distance between the guides 11 toenvelopes of different sizes. Stops 13 define the maximum outer positionof the guides 11.

The stack of envelopes 2 is positioned with one edge against a front(downstream) wall of the holder 3 for aligning the envelopes in relationto the feeding roller 4 and the deflecting surface 7 and for refrainingthe envelopes from displacement in transport direction 6.

The holder 3 is may be positioned in an inclined orientation, such thatthe stack of envelopes is leans against the front wall of the holder bygravity.

The holder 3 is provided with a moveable bottom surface and with abiasing member (not shown) for urging the stack 2 against the feedingroller 4 while maintaining the outer envelope 5 generally in theseparating plane 10. Thus, the outer envelope 5 of the stack 2 isbrought in a separating position in a separating plane 10 at the top ofthe stack 2, and is positioned with its leading edge 8 just above thefront wall of the holder 3 and near the deflecting surface 7.

The feeding roller 4 has a circumference and is positioned relative tothe holder 3 for contacting the envelope 5 in a contact area of itscircumference. The feeding roller 4 extends from beyond opposite lateralsides of the feeding path inwardly. It therefore contacts the envelope 5in side areas 15, 16 along opposite side edges of the envelope 5.

Spaced from the contact position between feeding roller 4 and theenvelope 5, the deflecting surface 7 is positioned, preferably as acontinuation of the wall of the holder 3. As the feeding roller 4, thedeflecting surface 7 extends in lateral direction from beyond thelateral sides of the feeding path inwardly across lateral outer portionsof the feeding path.

In the embodiment shown, the feeding roller 4 and the deflection surface7 both extends continuously from one lateral side of the feeding pathinwardly across the feeding path to the other, opposite lateral side ofthe feeding path. In alternative embodiment, shown in FIG. 4, feedingrollers 24 and deflection surfaces 27 of a separator 21 extend alongouter zones of the feeding path only.

Returning to the separator according to FIGS. 1-3, the feeding roller 4is connected to a drive 9 for driving rotation of the roller 4 about aheart line thereof. When the roller 4 is rotated, a friction force isexerted onto the outer envelope 5 and urges the envelope in a feedingdirection 6 tangential to the circumference of the feeding roller 4 andparallel to the separating plane 10.

For separating the envelope 5 from the stack 2, the feeding roller 4 isdriven by the drive 9 in a sense of rotation indicated by an arrow 19,exerting a friction force onto the outer envelope 5 in the separatingposition in the feeding direction 6 tangential to the feeding roller 4and parallel to the separating plane 10. This causes the outer envelope5 to be displaced in the separating plane 10 along the feeding path inthe feeding direction 6 and causes the leading edge 8 of the envelope 5to be urged against the deflecting surface 7 located downstream in thefeeding direction 6 of the contact area of the circumference of thefeeding roller 4. Accordingly, the outer envelope 5 encountersresistance depending on the bending stiffness of the envelope 5 andincreasing as the envelope is bent.

However, the friction force exerted by the feeding roller 4 onto theenvelope 5 causes the envelope to be urged along the deflecting surface7, which causes the envelope to bend out of the separating plane 10 asit is urged along the deflecting surface 7. The circumferential surfaceof the feeding roller 4 has a friction coefficient relative to paperthat is larger than the friction between the envelope in the separatingposition and the next envelope in the stack of envelopes 2. The maximumfriction force exerted on the next envelope in the stack 2 is thereforelower than the maximum friction force the feeding roller 4 can exert onthe outer envelope 5 and insufficient for overcoming the resistanceencountered when urged against the deflecting surface 7.

Since the feeding roller 4 and the deflection surface 7 engage the outerenvelope 5 in its lateral side areas 15, 16, which are the stiffestareas of the envelope, a relatively high resistance is encountered whenthe outer envelope 5 contacts the deflection surface 7. This resistancecan be overcome easily by the fraction force exerted by the feedingroller 4, but reliably refrains a next envelope, similarly subjected tobending forces in edge areas where it is relatively stiff, from beingentrained by the outer envelope 5.

Furthermore, by bending the envelope along its side edges, it is ensuredthat envelope is bent over its entire width and not only in the moreflexible centre part.

Since the feeding roller 4 and the deflection surface 7 extend acrossthe feeding path without interruption, the effect of engaging envelopesin areas along the side edges is achieved for envelopes of widelyvarying sizes and the bending stiffness of the envelopes is used overthe entire width of the envelope.

The deflecting surface 7 extends at an angle to the separating plane.The angle between the deflecting surface 7 and the separating plane isselected such that an outer envelope 5 entrained by the rotating feedingroller 4 is urged past the deflecting surface, whereas friction forcesbetween envelopes, by which a next envelope is entrained areinsufficient to overcome the resistance the next envelope encounterswhen it is deflected by the deflection surface. In practice, the anglebetween the deflecting surface and the separating plane is preferablybetween 85 and 140° and more preferably between 110 and 130°.

When envelopes of different width are processed, the relatively stiffside edge areas of the envelopes engage different sections of thedeflection surface. By providing that the deflecting surface has afriction coefficient that is uniform across its width, the resistanceencountered by envelopes being separated varies only little with widthof the envelopes of the envelopes.

The friction coefficient of the deflecting surface relative to paper ispreferably smaller than the friction coefficient between rubber andpaper, which is about 1. More preferably, the friction coefficient ofthe deflecting surface relative to paper is smaller 0.8, so that it issmaller than the friction coefficient between rubber and paper by asubstantial amount.

The friction coefficient of the deflecting surface relative to paper ispreferably larger than the friction coefficient between metal and paper,which is about 0.1. to 0.4. More preferably, the friction coefficient ofthe deflecting surface relative to paper is larger than 0.5 or, morepreferably, 0.6, so that it is smaller than the friction coefficientbetween metal and paper and larger than the friction coefficient betweenenvelopes by a substantial amount.

The bending distance, that is the distance between the point of contactarea of the circumference of the feeding roller 4 and the most remotepoint of contact between the envelope being separated and the deflectingsurface 7, is preferably between 6 and 12 mm, and more preferablybetween 7.5 and 10.5 mm, for a feeding roller 4 having a diameter of 25mm.

Once the leading edge 8 of the envelope 5 is deflected out of theseparating plane 10, the leading edge 8 is for example led into a nip ofa transport track 14 formed by pairs of opposite conveyor belts.

Other variations to the disclosed embodiments can be understood andeffected by those skilled in the art in practicing the claimedinvention, from a study of the drawings, the disclosure, and theappended claims.

1. A method for separating envelopes, in which method providing aseparator for separating envelopes, said separator comprising: a holderincluding a support and lateral guides defining opposite lateralenvelope guide edges; at least one feeding roller having a circumferenceand at least two portions; at least one deflecting surface including twoportions and having a friction coefficient uniform across its width; theat least one feeding roller and the at least one deflecting surfacebeing positioned such that: they bound a feeding path, said feeding pathhaving a width defined between opposite lateral edges that are in-linewith the opposite lateral envelope guide edges; the two portions of theat least one feeding roller extend from at or from beyond oppositelateral sides of the feeding path inwardly across at least lateral outerportions of the feeding path; the two portions of the at least onedeflecting surface extend from at or from beyond opposite lateral sidesof the feeding path inwardly across at least lateral outer portions ofthe feeding path; and the deflecting surface extends at least the widthof the feeding path or a width of the at least one feed roller; saidmethod further comprising the steps of: providing a stack of envelopesin the holder such that an outer one of the envelopes is in a separatingposition in a separating plane; contacting the outer one of theenvelopes in the separating position in a contact area of itscircumference by the at least one feeding roller, such that a frictionforce is exerted onto the envelope; rotating the feeding roller suchthat the outer one of the envelopes is urged in a direction tangentialto the circumference and parallel to the separating plane; wherein whenthe outer one of the envelopes is provided in the separating positionthe at least one deflecting surface extends at an angle to saidseparating plane at least from a position in the separating plane;wherein during contacting of the outer one of the envelopes the at leastone deflecting surface is spaced from the contact area in saidtangential direction; and wherein when the outer one of the envelopes isurged in a direction tangential to the circumference and parallel to theseparating plane the leading edge of the envelope in the separatingposition is deflected in said tangential direction along the separatingplane and is passed along the at least one deflecting surface.
 2. Amethod according to claim 1, wherein the method comprises the step ofusing a separator of which the at least one feeding roller extendscontinuously across the feeding path.
 3. A method according to claim 1,wherein the method comprises the step of using a separator of which theat least one deflecting surface extends continuously across the feedingpath.
 4. A method according to claim 1, wherein the method comprises thestep of using a separator in which the angle between the deflectingsurface and the separating plane is between 85 and 140°.
 5. A methodaccording to claim 1, wherein the method comprises the step of using aseparator in which the friction coefficient of the deflecting surfacerelative to paper is smaller than
 1. 6. A method according to claim 1,wherein the method comprises the step of using a separator in which thefriction coefficient of the deflecting surface relative to paper islarger than 0.4.
 7. A method according to claim 1, wherein the methodcomprises the step of using a separator in which the angle between thedeflecting surface and the separating plane is between 110 and 130°. 8.A method of to claim 1, wherein the method comprises the step ofadjusting said lateral guides for changing a spacing therebetween.